Rittman Lake and the Overrunning Sequence

gwiles December 6, 2024 10:01 am

The group posing in front of some generations of draglines at the Zollinger Pit in Rittman. Many thanks to the operators for giving us permission to spend a spectacular afternoon at the site.

Figure 1. Map showing some the the local topographic features. A lake resided in the valley prior to the Laurentide ice advance into the basin. The lake at some point drained down the Killbuck Spillway to the west.

 

Figure 2. This stylized sedimentary sequence from T.V. Lowell provides a framework for the site. Preglacial lacustrine setting overrun by the ice sheet.

Figure 3. The base of the sequence is a series of varve-like sediments consisting of silt-clay couplets. The group determined that is this high sediment charged environment these were likely not annual but diurnal (daily).

Figure 4. The swallows build their nest into the silt and this sequence overall is coarsening upward. Note the vertical downcutting along the boundaries of joint in this unconsolidated sediment pile.

Figure 5.  An introspective moment reflecting on the environment at the bottom of a proglacial lake just prior to advance of the Laurentide ice sheet into the basin.

 

Figure 6. The group working our the direction of the paleocurrent based on a series of climbing ripples with clay drapes – could they be daily couplets?

Figure 7. This facies model is a good conceptual cartoon of the setting.

Figure 8. A rare moment when the entire class was working. The upper unit record the glacial tills recording the ice advance and retreat from the site.

Figure 10. As the ice advanced and thickened over the site it smear the sediments into a deformation till, and as the ice thickened and effective normal stress increased the till was lodged onto the sediment pile.

Figure 11. The lodgement till at the top of the sequence, which, in turn, is capped by a melt-out till. The class was able to determine the ice was not absent from the site.

Figure 12. The melt-out till showing fluid escape structures and ball and pillow structures indicating loading and melt out.

 

Figure 13. Closeups of the ball and pillow structures.

Figure 14. Dropstone were evident and here we see a dropstone made of a stone and a till clast. This indicates icebergs in the lake dumping sediments into the lake.

Figure 15. A portion of the class spent much of the time mining gypsum crystals. The presence of gypsum crystals at the pit indicate a desert environment? We explained the gypsum as a case of saturated groundwater and, of course, kinetics.

Figure 16. Some healthy skepticism about the site and the origin of the sediments.

 

Posted in Uncategorized | 1 Comment

A Delta in the Little Killbuck Valley (Wooster Memorial Park)

gwiles December 5, 2024 4:31 pm

The Geomorphology (GEOM24) class posing along the Little Killbuck River Valley. Looming in the background is the delta built into Lake Killbuck during immediate post-glacial times about 14,000 years ago. The sediments are so well exposed, in part, due to some recent illegal hydraulic mining  for sand and gravel.

Figure 1. Two versions of the measured section showing the coarsening upward sequence of sediment making the Gilbert-type delta built into the paleolake. This sequence of unconsolidated sediments sits on the Mississippian siltstones and shales.

Figure 2. The shale is evident to the left of the class members. Clays, silts and colluvium marks the flooding of the valley and the beginning of the bottomset beds in the delta.

Figure 3. The foreset beds are composed to silt and sands with frequent clays and deformation reflecting changes in water levels and the high rates of sedimentation and slumping.

Figure 4. A “flow roll” of a mix of foreset sands and lacustrine clays likely deformed through slumping along the delta front. Note the liesegang rings in these likely 14,000 year old sediments.

Figure 5. A somewhat enigmatic fracture clay layer is likely due to a ephemeral increase in lake level, or a change in the delta depocenter. There was some discussion of a ice readvance, however, this is unlikely.

Figure 6. Front lower left to upper right – the photo captures the disconformity at the bottom, the foresets to the upper right and the cut and fill structures of the topsets. The diagram below summarizes the overall structure of the delta.

Thanks for Nick Wiesenberg for helping with logistics in all the Geomorphology fieldtrips this past semester and for digging many holes.

 

Posted in Uncategorized | 1 Comment

Geomorphology (GEOM24) – Soils on the Golf Course

gwiles December 4, 2024 4:38 pm

The group gearing up to describe and map soils in the old growth stand just east of the College Golf Course.

Guest bloggers: Lynnsey, Cate, Evie, Chanel, Lilly and Amanda

 

Figure 1. Diagram showing the formation of the glacial landform that the Wooster soils is formed on – it is a kame terrace with parent material of sand and gravel with a venerr of loess.

Figure 2 – the College golf course soils – they are mapped as the Wooster – Riddle silt loam and they are photogenic – the A horizon is on the right, B in the middle and on the left is the C horizon (partially weathered parent material).

Figure 3. the stars on this ternary diagram are the A (orange star), B (red) and C (blue star).

Geochemistry of the soils (Figure 4):

  • In the A horizon: Calcium and Phosphorus build up from fertilizers used applied to the nearby golf course 
  • Sodium likely from road salt
  • Barium, Cobalt, Sulfur, Manganese and Lead from past coal burning in the former campus coal plant t
  • In B horizon: Translocated Aluminum and Iron  

Figure 5. Describing the soil in the pit and taking measurements of magnetic susceptibility.

Figure 6. The coring team described a transect of soils cores along the kame terrace.

Figure 7. A representative soils core described and keyed into the soil pit via mapping.

Figure 8. As it turns out there are old growth forest (this white oak is over 300 years old) this indicates  that the soils were were examining have not been plowed.

Figure 9. An example of the relatively newly-invasive asian jumping worm. This critter is non-burrowing and has the behavior of a snake as much as an earthworm. It quickly east leaf litter and does not mixed the soils as a result the surface of the soils in this forest now consists of a mantle of worm castings. Note in the scenes above there is very little undergrowth.

 

Figure 10. Somehow Cate found a golf ball and a club and finished the day on the 7th fairway.

Posted in Uncategorized | 1 Comment

Geomorphology (GEM24) Part 3 – Browns Lake for Soils

gwiles December 4, 2024 3:55 pm

Guest bloggers: Grace, Hayden, Vince and Ethan

The group working with soils at Browns Lake Bog Preserve. The goal was the dig three soils pits and examine the soil catena from the top of a kame to the base controlling for the topographic control on soil’s texture, structure and composition.

Figure 1. A nearby kame (hill of sand and gravel of glacial origin) within the kame and kettle topography of the region.

Figure 2. The kame and kettle topography of the Browns Lake site the kame in the middle of the image was the location of the soils transect. We chose the north-facing side of the kame as the southern faces are strongly bioturbated by groundhogs (aka whistle pigs) and other varmints.

Figure 3. Soils pit at the apex of the kame showing the loess cap on the kame sand and gravel is the parent material.

 

Figure 4. At mid slope a highly trained team eagerly digs a pit in the kame.

Figure 5. Team 2 somewhat further downs slope taking careful observations.

Figure 6. At the based of the kame the team noted an onlapping sequence of detrital peat, which changed the parent material and suggested that the water levels in the bog have been variable.

 

Figure 7. The dendro team cores trees on the flats to get an idea of the age of the substrate.

 

Figure 8. More tree ages.

 

Figure 9. Nick downloaded a pressure transducer installed in a well in the bog. These data show a full three years of hourly data that includes water levels (black line) and the water temperature records (blue line).

The team looking a bit skeptical about the idea of a soil catena, a healthy does of critical thinking.

Posted in Uncategorized | 1 Comment

Geomorphology (GEOM24) – Part 2 of What we learned

gwiles December 4, 2024 10:43 am

Guest blogger: Mary, Molly, Ihaja and Li

Figure 1. Fern Valley is a property donated to the College of Wooster by former faculty Dr. Wilkin and his partner Betty that now serves as a field station. Down the center of the valley runs Wilkin Run, which is a north flowing meandering stream that empties into Odell Lake.  Here the class is standing on hanging wall  of a scarp that reveals the slumping in the region.

Figure 2. LiDAR map of the area. Note the Wilkin Run Valley and how it is incising into the surrounding pile of glacial sediments. Note the arcuate scarps along the stream. 

Figure 3. An oblique view of the scarp from Bing maps. This scarp is a major feature on the property and is an ongoing mass movement as the stream down cuts the ice-contract stratified drift above slides on a lacustrine layer below causing the mass movement.

Figure 4. A look up at an exposure in the the glacial sediments. Here is an ice-contact stratified drift sequence that includes clays incorporated into the sediments as the glacier advanced into a lake.

Figure 5. The Geologic History of Fern Valley (Source: ODNR site, notes and sketches, ppts).

Fern Valley began as a lake with a thick layer of clay at the bottom.  This clay layer contains varves, which is a couplet of clay and silt that marks each year.  A glacier advanced around 20,000 years ago, which deposited large amounts of sand and gravel, creating a buried valley.  This sediment was stratified due to the melting of the glacier and there was also a layer of loess deposited on top.  Wilkin Run began to cut down into the layers of sand, gravel, and clay to create a deeper valley.   

The surface of the valley is a series of uplifted faults with pores in between. Over time rainwater gets caught in the pores and is trapped by the underlying clay sediments. As the layer of moving water in the clays builds up the pressure of the pore water increases, loosening the overlying sediment, allowing for gravity to take effect on the sediment and create slumps. A slump is a form of mass movement that forms a scarp and the slump itself on two sides of a normal fault scarp. Gravity moves the slump further down the cut slope of the stream 

Figure 6. A team of experts investigates the imbricate nature of the modern alluvium deposited just downvalley of a rock out crop. Note the angular nature of the clasts.

Figure 7. The College of Wooster has been collecting hourly climate data including water level, pressure, precipitation, and temperature from Fern Valley since 2012.  This graph shows the hourly temperature data from the past 12 years.  The maximum temperatures have slightly risen, but most of the increase can be seen in the minimum temperatures and the minimum cold season temperatures have warmed. 

Special Thanks to Nick Wiesenberg, our Geologic Technician, and Fred Potter our excellent bus driver. 

 

Posted in Uncategorized | 1 Comment

Geomorphology (GEOM24) – Spangler Gorge (Part 1)

gwiles December 3, 2024 10:01 pm

Guest bloggers: Damien, Rheo, Elliot and Arron: On September 9th the 2024 Fall Geomorphology Class took a trip to Spangler Gorge in Wooster Memorial Park. Here the students studied how the valley formed around Rathburn Run as well as the various unconformities that could be seen throughout the gorge. On a later trip the group visited a new site along the Little Killbuck River drainage and described the sediments in a delta built into glacial Lake Killbuck.

Figure 1. LiDAR map of the Wooster Memorial Park. The lower drainage is in Wooster Memorial Park (Rathburn Run) and the larger drainage to the north is the Little Killbuck drainage.

Figure 2. (above) The local Mississippian bedrock in the way into the gorge is creeping downhill due to unloading. (lower) Tree throw is a major sediment transport mechanism especially after some major storms over the last few years.

Figure 3. Once in the gorge the group discusses the various unconformities in the park. The drought early in the fall was evident with very low flow throughout the gorge.

Figure 4. A glacial erratic from Canada- the is from an outcrop to the Gowganda Tillite in Ontario. This dates back to the Snowball Earth interval in the Proterozoic and was brought down by various advances of the Laurentide Icesheet.

Figure 5. Unconformity (disconformity) with Holocene alluvium overlying the Mississippian bedrock. Note the knickpoint in the rock and its jointing.

Figure 6. Hayden pointing out an unconformity with holocene alluvium overlying a Pleistocene lodgement till.

Figure 7. Conjugate joint sets in the floor of the gorge – this angularity, in part, determines the zig-zag stream pattern of Rathburn Run as it continues to entrench into the bedrock.

Figure 8. Siltstone being undercut by Rathburn Run, note the varying structure of the rock contributing to a large range of rock strengths. This outcrop is an outlier in the gorge eroded by generations of ice ages and fluvial downcutting.

Figure 9. Debris cone at the base of the bedrock – these fans build in the dry fall and then get swept away with floods and incorporated in the alluvium.

Figure 10. A small alluvial fan built out into the valley alluvium. The fallen tree in the upper right has fallen along the long axis of the fan.

Figure 11. Debris flow at the unconformity with the bedrock and overlain by alluvium.

Erosion in Spangler Gorge has been rapidly increasing over the last several decades. A major factor driving this change seems to be due to climate change bringing in greater amounts of precipitation with more extreme weather patterns, often flooding the system with large amounts of water and increasing the stream’s strength and velocity. The increased strength of the stream (Figure 12) has led to it downcutting, and eventually being unable to reach its floodplains. Floodplains have an important role in managing the energy from flooding streams, allowing them to overflow, spread out, and slow down. However, now that the floodplains have become inaccessible, the high kinetic energy during a flood stays condensed within the streambed, leading to further erosion. Notably, this intensity causes undercutting to occur in the surrounding rocks which eventually causes them to become unstable and collapse, dumping more sediments into the rushing water. While a healthier stream system would be able to eventually rebuild its banks and reach its floodplains again, the velocity of the stream in Spangler erodes sediments faster than they can be deposited, leading only to more widening and downcutting of the streambed. It seems unlikely, with the intensifying climate of the area, that Spangler will be able to rebuild its banks on its own and become more stabilized. However, there could be opportunities in the future for stream restoration projects to try and reestablish healthier and stronger banks for the stream.

Figure 12. Discharge from the nearby Killbuck Creek. Rathburn Run is a tributary to the Killbuck. Note the shift in the mid-1970s to high annual streamflow. Our working hypthesis is that the rivers and streams in the NE Ohio region are now downcutting over the past few decades at faster rates than they have for several thousand years.

 

Posted in Uncategorized | 1 Comment

Carbonate hardgrounds at Wooster

Mark Wilson September 25, 2024 1:34 pm

On the second floor of Wooster’s Scovel Hall, in a room behind the main teaching laboratory, are six cabinets completely full of labelled rocks and fossils (see below). There is even an additional set of specimens too large for the cabinets stored under the eaves in the attic space on the third floor, and in various other cabinets are suites of fossil hard substrates. This is The College of Wooster’s carbonate hardground collection, unique in the world for its size and diversity.

Carbonate hardgrounds are rock surfaces that were once cemented calcareous sediment layers on seafloors (Palmer, 1982; Wilson and Palmer, 1992). The top image of this post shows a hardground from the Upper Ordovician of southwestern Ohio. It is a limestone distinguished by a surface with encrusting organisms, borings, and nestlers in cavities showing it was an ancient lithified seafloor — a rocky substrate in a shallow Ordovician sea. The cementation of carbonate hardgrounds is synsedimentary, meaning they were formed by precipitation of carbonate crystals between sediment grains on the seafloor itself, not long afterwards following deep burial (Erhardt et al., 2020).

Even though the process of forming a carbonate hardground is geochemical, they are most often recognized by biological phenomena that show they were hard marine seafloors with associated hard substrate-dwelling organisms (sclerobionts). These sclerobionts include encrusting organisms (such as bryozoans, crinoids, oysters, barnacles and the like), borings (often made by polychaete worms, clams, snails and sea urchins), and nestlers that lived in cracks, crevices and caverns of these rocks. In the image above you can see two rugose corals that nestled in shallow concavities on the hardground surface. (It is a closer view of the Ordovician hardground pictured at the top.)

Brett and Liddell (1978, fig. 9, p. 344) constructed this beautiful diagram reconstructing a Middle Ordovician hardground found in southern Ontario, Canada. It shows encrusting bryozoans, stemmed echinoderms, and cross-sections of borings cut into the rock surface.

The origin story for Wooster’s hardground collection begins in 1984. My wife Gloria and I were exploring sites in northern Kentucky for an upcoming Wooster paleontology course field trip. We stopped by a muddy exposure in Boone County and I immediately saw the above flat cobble weathered out of the outcrop. It was encrusted with beautiful fossils, and had many cylindrical borings. There were hundreds of similar cobbles scattered about. Most were encrusted and bored on both sides, so I knew there was a paleoecological narrative here.

Here is a close view of another of these Ordovician cobbles in Kentucky. The fine branching network is the bryozoan Corynotrypa, and the stellate encruster is an edrioasteroid echinoderm (Cystaster stellatus). I was enchanted with this little hard substrate community and wrote a paper about how they show a rare example of ecological succession in the fossil record (Wilson, 1985). I wanted to pursue more research on these sclerobionts (even though that term was yet to be coined!).

Shortly after that Kentucky work, I took my first research leave in 1985 to Oxford University in England. I told my host in the Department of Earth Sciences that I was interested in the paleoecology and evolution of hard substrate communities. He quickly recommended that I meet two young paleontologists. The first was Tim Palmer at Aberystwyth University on the western coast of Wales. I contacted Tim and he generously invited me and my little family to his home. Meeting Tim changed my life. Tim had done pioneering work on carbonate hardground communities in the 1970s, resulting in several classic hardground papers (e.g., Palmer and Fürsich, 1974; Palmer and Palmer, 1977) and the first summary of hardground communities through time (Palmer, 1982). During his North American work, he and his wife Caroline collected an astonishing number of hardground samples from Paleozoic and Mesozoic strata. They deposited this material in the US National Museum in Washington, DC, and in the early 1980s it was transferred to Wooster to form the nucleus of our hardground collection. Tim and I, along with other colleagues and students, have added to that collection ever since.

The second English paleontologist I was encouraged to meet in 1985 was Paul Taylor of the Natural History Museum in London. As with Tim Palmer, Paul and I quickly became close colleagues and friends. Paul specializes in bryozoans of all types, as well as other organisms found encrusting and boring hard substrates. In fact, it was Paul and I who invented the term sclerobiont (Taylor and Wilson, 2002 and 2003). Over the decades, Paul also contributed to the Wooster hardground collection, as well as to other suites of sclerobionts on other hard substrates. I can’t say enough about what fantastic friends and colleagues Tim and Paul have been for me, and how much they influenced paleontology at Wooster through their work with many of our students. (And yes, they both seem to have fancied pink shirts for fieldwork!)

About 20 years I met the remarkably productive Estonian paleontologist Olev Vinn, currently an Associate Professor of Paleontology at the University of Tartu. We have common interests with hard substrate communities and very quickly began to look at hardground faunas in the Baltic (for examples, see Vinn and Wilson, 2010a and 2010b; Vinn et al., 2015). Samples from these and other Baltic Ordovician hardgrounds have been added to the growing Wooster collections. Olev and I have since done diverse work on sclerobionts, especially borings and tube-dwellers. Lately we’ve been concentrating on symbiotic relationships in hard-substrate faunas. Much of this work has recently included our Estonian colleague Ursula Toom.

Ordovician (Katian) hardground in cross-section from the Vasalemma quarry in Estonia (GIT 222-499). The borings are the ubiquitous Trypanites. From Figure 9 of Vinn et al. (2015).

Also at the turn of the century I met another English paleontologist: Caroline J. Buttler, currently Head of Collections Development at Amgueddfa Cymru-National Museum Wales. (Image from her museum staff profile.) We share a passion for bryozoans, especially big lumpy trepostomes from the Ordovician. She headed a project describing an Upper Ordovician hardground complex from northern Kentucky in which the hardgrounds were eroded and undermined on the seafloor to form caverns with hardground roofs (see below). Samples of these hardgrounds are in several drawers of Wooster’s hardground collection. The roadside outcrop from which they were collected no longer exists, so these specimens are the only record.

One of the cave-forming hardgrounds from the Upper Ordovician of northern Kentucky described by Buttler and Wilson (2018). The large lump on the surface is a trepostome bryozoan colony. The vertical holes are the boring Trypanites. This looks like a typical bored and encrusted carbonate hardground, but in this image it is upside-down!

This is the actual orientation of the Buttler and Wilson (2018) hardground. It is the roof of a small cavern. The bryozoan was attached to the ceiling and hung down into the little cave. The borings were actually excavated upwards into the limestone roof. Pretty cool story.

Many other professional colleagues, amateur collectors, and Wooster students have added to the Wooster carbonate hardground collection, as well as to other fossil hard substrate assemblages. I wish I could name them all!

Here are some highlighted carbonate hardgrounds represented in Wooster’s collections. Above is a hardground from the Upper Ordovician of southeastern Ohio. We can identify it as a hardground by the abundant small holes punched into the surface (which are the common Trypanites borings). What is notable in this specimen are the irregular cavities, including the straight cone at the top. These are molds of aragonitic shells like those of many bivalves, gastropods, and cephalopods. (The conical one is from a straight nautiloid cephalopod.) This specimen represents a critical observation that these aragonite shells dissolved on the seafloor, producing fluids that precipitated calcite crystals in the sediments, forming the hardground that was later bored and encrusted. This process, a feature of Calcite Sea geochemistry, was described by Palmer et al. (1988).

This slab shows an Upper Ordovician hardground surface in southwestern Ohio with the ovoid borings of bivalves. These borings were described as Petroxestes by Wilson and Palmer (1988).

This is an encrusted hardground from the Middle Ordovician Kanosh Shale of west-central Utah. Most of these encrusters are eocrinoids, an early echinoderm. This hardground series was described by Wilson et al. (1992).

The above hardground sample is also from the Kanosh Shale. The large lump on the left is the encrusting bryozoan Nicholsonella.

This hardground is from the Carmel Formation (Middle Jurassic) of southwestern Utah. The light-gray layer above the ruler shows numerous bivalve borings known as Gastrochaenolites. It was described and interpreted by Wilson and Palmer (1994) and Wilson (1998). The Carmel Formation has been a popular topic for Wooster Independent Study students over the past 30 years. Search for it in this blog!

This is a polished cross-section of a Carmel Formation hardground. The layered unit below is the hardground, complete with Gastrochaenolites borings. The top half shows layers of encrusting oysters.

This is a bivalve-bored carbonate hardground in the Ora Formation (Upper Cretaceous, Turonian) near Makhtesh Ramon in the Negev of southern Israel. It makes a very distinctive marker horizon in the Cretaceous of this region.

I want to end this tour of the Wooster Carbonate Hardground Collection with a specimen that is not technically a carbonate hardground, but interpreted by its common features with hardgrounds. This is a “rockground”, which is an informal term for a sedimentary hard substrate that was encrusted and bioeroded as a rock surface, not a cemented seafloor. This is a wave-eroded coral surface from the Pleistocene exposed on the coast of San Salvador Island, The Bahamas. The small holes are borings formed by clionaid sponges and given the name Entobia. A scleractinian coral encrusts the surface at the upper right. This eroded surface records sea-level changes during the Last Interglacial highstand (White et al., 1998; Wilson et al., 1998; Thompson et al., 2011). You can read the story in this earlier blog post. It was a project that took the lessons of studying carbonate hardgrounds into a bit of paleoclimatology research.

This is thus a description of the Wooster Carbonate Hardground Collection, which because of its diverse history is unique in the world. If you are ever on the second floor of Scovel Hall, take a peek in the cabinets to see these wonderful rocks and fossils. They have been at the center of my geological and paleontological research program, and thus also for generations of Wooster Independent Study students.

 

References:

Brett, C.E. and Liddell, W.D., 1978. Preservation and paleoecology of a Middle Ordovician hardground community. Paleobiology 4: 329-348.

Buttler, C.J. and Wilson, M.A. 2018. Paleoecology of an Upper Ordovician submarine cave-dwelling bryozoan fauna and its exposed equivalents in northern Kentucky, USA. Journal of Paleontology 92: 568 – 576.

Erhardt, A.M., Alexandra V. Turchyn, A.V., Dickson, J.A.D., Sadekov, A.Y., Taylor, P.D., Wilson, M.A. and Schrag, D.P. 2020. Chemical composition of carbonate hardground cements as reconstructive tools for Phanerozoic pore fluids. Geochemistry, Geophysics, Geosystems 21(3): e2019GC008448 (https://doi.org/10.1029/2019GC008448).

Palmer, T.J., 1982. Cambrian to Cretaceous changes in hardground communities. Lethaia 15: 309-323.

Palmer, T.J., and Fürsich, F.T., 1974. The ecology of a Middle Jurassic hardground and crevice fauna. Palaeontology 17: 507-524.

Palmer, T.J., Hudson, J.D., and Wilson, M.A., 1988. Palaeoecological evidence for early aragonite dissolution in ancient calcite seas. Nature 335: 809-810.

Palmer, T.J., and Palmer, C.D., 1977. Faunal distribution and colonization strategy in a Middle Ordovician hardground community. Lethaia 10: 179-199.

Taylor, P.D. and Wilson, M.A. 2002. A new terminology for marine organisms inhabiting hard substrates. Palaios 17: 522-525.

Taylor, P.D. and Wilson, M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103.

Thompson, W.G., Curran, H.A., Wilson, M.A. and White, B. 2011. Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas corals. Nature Geoscience 4: 684–687.

Vinn, O. and Wilson, M.A. 2010a. Microconchid-dominated hardground association from the late Pridoli (Silurian) of Saaremaa, Estonia. Palaeontologia Electronica 13(2):9A, 12 p.

Vinn, O. and Wilson, M.A. 2010b. Early large borings from a hardground of Floian-Dapingian age (Early and Middle Ordovician) in northeastern Estonia (Baltica). Carnets de Géologie / Notebooks on Geology, Brest, Note brève / Letter 2010/04 (CG2010_L04).

Vinn, O., Wilson, M.A. and Toom, U. 2015. Bioerosion of inorganic hard substrates in the Ordovician of Estonia (Baltica). PLoS ONE 10(7): e0134279. doi:10.1371/journal.pone.0134279.

White, B.H., Curran, H.A. and Wilson, M.A. 1998. Bahamian coral reefs yield evidence of a brief sea-level lowstand during the last interglacial. Carbonates and Evaporites 13: 10-22.

Wilson, M.A. 1985. Disturbance and ecologic succession in an Upper Ordovician cobble-dwelling hardground fauna. Science 228: 575-577.

Wilson, M.A., 1998. Succession in a Jurassic marine cavity community and the evolution of cryptic marine faunas. Geology 26, 379-381.

Wilson, M.A., Curran, H.A. and White, B. 1998. Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.

Wilson, M.A., and Palmer, T.J. 1988. Nomenclature of a bivalve boring from the Upper Ordovician of the midwestern United States. Journal of Paleontology. 62: 306–308.

Wilson, M.A. and Palmer, T.J. 1992. Hardgrounds and Hardground Faunas. University of Wales, Aberystwyth, Institute of Earth Studies Publications 9: 1-131.

Wilson, M.A. and Palmer, T.J., 1994. A carbonate hardground in the Carmel Formation (Middle Jurassic, SW Utah, USA) and its associated encrusters, borers and nestlers. Ichnos 3, 79-87.

Wilson, M.A., Palmer, T.J., Guensburg, T.E., Finton, C.D., and Kaufman, L.E. 1992. The development of an Early Ordovician hardground community in response to rapid sea-floor calcite precipitation. Lethaia 25, 19-34.

Posted in Uncategorized | Tagged , , | Leave a comment

A Wooster Geologist visits Fort Meigs, Ohio

Mark Wilson September 20, 2024 8:54 pm

Today my wife Gloria and I visited the reconstructed Fort Meigs in the northwestern corner of Ohio in Perrysburg, just south of Toledo. It was a beautiful day and we practically had the place to ourselves. It was our first trip since I started my retirement from The College of Wooster. It felt a little naughty to be there during a work day! The above image is of one of the reconstructed fort blockhouses from the outside. Fort Meigs is sited on “Ohio’s War of 1812 battlefield”.

This inside view of another blockhouse shows the basic construction of the fort — blockhouses with cannon and rifle gunports connected by a strong wooden palisade. The fort is reconstructed as it would have appeared in 1813

This reconstruction gun position overlooks the Maumee River, which is very difficult to see through all the vegetation.

Fort Meigs was constructed by American troops during the bitter winter of 1813. It was designed to be a supply depot for military operations north into Canada and Michigan, as well as for protection of Ohio from invasion by British and Native American forces to the north. General William Henry Harrison was the American commander. The British commander was General Henry Procter, and the Indian warriors were under Chief Tecumseh. On April 28, 1813, the British and Indians began a siege of Fort Meigs, and a significant and bloody battle was fought outside the walls on May 5th. The Americans held the fort during that siege and a second siege attempt in July 1813. The British and Indians retreated and ended the last invasion threat to Ohio.

This post is not to describe in detail the battles at Fort Meigs, but to discuss the geological reasons Fort Meigs was built in this particular place.

This map shows the geography, towns and forts in the Detroit region during the War of 1812. Fort Meigs is shown in the southwest corner of the map on the Maumee River. The river is key to this story. It was a major transportation artery from Lake Erie into northern Indiana. The Maumee River watershed was otherwise difficult to traverse because of the Great Black Swamp, now entirely drained.

Here in this 1813 map we see the position of Fort Meigs overlooking the Maumee River. The British siege batteries of April and May 1813 are shown to the north and east of the fort. Note that the river flows to the northeast. Critically, just upstream from the fort are “Rapids”. Boats traveling upriver must unload and portage around these rapids. Fort Meigs is situated at this critical point where anyone continuing upriver is subject to cannon and gunfire.

This is another 1813 map of the Fort Meigs area. The Maumee River was sometimes called the “Miami”, which is confusing in Ohio because there is another Miami river.

Today Fort Meigs still overlooks the Maumee River, bit of course the topography and hydrology here has been highly engineered since 1813. The rapids still exist, though, upstream from the fort and are not visible because of high water levels at the time of this Google Earth image.

So why do rapids appear at this interval of the Maumee River? Here’s where the geology comes in. In the above map from Ehlers et al. (1951), we see a contact between two geological units at the downstream boundary of the rapids. The red arrow indicates where the river flows off the Tymochtee Dolomite onto the underlying Greenfield Formation. Both of these are Silurian carbonate units. Critically, the Tymochtee Dolomite is more resistant than the upper beds of the Greenfield Formation. The riverbed on the Tymochtee is therefore more rocky, thus producing the rapids. Fort Meigs, at the small blue “x” on the map, took advantage of this change in the navigability of the river. Geology controlled this War of 1812 battlefield.

We didn’t go down to the rapids today, so I got the above image of the rapids from Google Maps. Slabs of the Tymochtee Dolomite are visible in the riverbed and banks. A much more evocative image of these carbonate rocks can be seen here. I learned a new word for a biome through this research: alvar. These flooded, flat carbonate exposures support a unique flora and fauna that is periodically wet and dry. The rapids here are part of the Maumee River alvar.

Reference:

Ehlers, G.M., Stumm, E.C. and Kesling, R.V. 1951. Devonian rocks of southeastern Michigan and northwestern Ohio. Stratigraphic field trip of the Geological Society of America, Detroit Meeting (November 1951)

Posted in Uncategorized | Tagged , , | Leave a comment

And sometimes it rains.

Mark Wilson July 17, 2024 7:42 pm

Today I took Peter, Lauren and Evie on another afternoon local field trip, this time to Wooster Memorial Park (Spangler). We wanted to repeat the enjoyable exploration we had last week in Lodi Community Park. This time, though, we got thoroughly drenched by a small thunderstorm cell that just seemed to hover over us. The students managed to get these images.

It started out well! Evie and Lauren found salamanders in the creek bed.

But then the rain got serious!

It was a steady downpour, forcing us to exit once we were thoroughly soaked.

The trails became streams on our hike back to the car. Still, it was a fun adventure, if a bit short!

Posted in Uncategorized | Tagged , | Leave a comment

Klawock to Ketchikan

gwiles July 17, 2024 3:48 pm

Guest bloggers: Amanda Flory and Mihalis Protopapadakis

Carnivorous sundews found in Balls Lake muskegs.

On our last full day at Prince of Wales Island, we explored the trail around Balls Lake, in Tongass National Forest. The AYS team helped us core trees of several different species. We then returned to the AYS headquarters in Klawock and taught them how to mount tree cores and analyze them under the microscope. We also celebrated Nick’s birthday!

The following morning we took the ferry back to Ketchikan and spent the day climbing Dude Mountain. There, we collected more cedar samples in a muskeg and a bear trail along the edge of a cliff. We spent the final day of our trip exploring the city of Ketchikan and the nearby beaches.

Bob and Dr. Wiles searching for cedars in the rainforest.

Salmon-spawing stream flowing out of Balls Lake.

Gary supervising tree-core collection at a Forest Service site.

The Wooster team and AYS group deep in the woods of Balls Lake.

Gary’s cedar cookie showcasing abnormal ring characteristics.

Freshly picked blueberries.

The team hiking along the Balls Lake trail.

The team skillfully balancing on a slippery log.

Teaching the AYS group how to process and examine tree cores back at headquarters.

The team sharing excitement over dendrochronology.

Celebrating Nick’s birthday with a delicious cake that David baked.

Happy Birthday Nick!

A bald eagle spotted on the drive to Dude Mountain.

Couple of dudes on Dude Mountain.

The view from the bear trail along the cliff.

Amanda and Proto coring a yellow cedar.

The famous Creek Street boardwalk in southern Ketchikan.

The view from the team’s airbnb.

On the final day, the team visited tidal pools along the coast.

A starfish saved from low tide.

This trip was a wonderful experience. Thank you to all the great people we met along the way! Also a big thank you to Dr. Wiles and Nick for their guidance and these great memories. A big thank you to Bob Girt and the Alaska Youth Stewards Group in Klawock who hosted our trip on Prince of Wales Island. This work was supported by Grant NSF P2C2-2002454 and the Department of Earth Sciences at Wooster.

Posted in Uncategorized | Tagged , , | 1 Comment